This invention relates generally to gas separation devices such as electrostatic precipitators and, more particularly, to an adapter for electrical discharge wire electrode assemblies that permits existing wire electrode assemblies to be converted to wire electrodes of the type comprising an elongated wire having its opposite ends terminating axially within two identical shrouds, each of the shrouds shaped as an elongated rod terminating in a combined frusto-cone and enlarged button head.
Conventional electrostatic precipitators are used to remove foreign particles from a gas stream and are generally described in Cummings, et al., U.S. Pat. No. 3,109,720; Quintilian, et al., U.S. Pat. No. 3,483,670; Phyl, U.S. Pat. No. 2,866,517; Archer, et al., U.S. Pat. No. 3,485,011; Wiemer, U.S. Pat. No. 3,483,671; Ertl, el al., U.S. Pat. No. 3,783,589; Hull, U.S. Pat. No. 2,666,495 and Heer et al., U.S. Pat. No. 3,774,372. The electrostatic precipitators are generally made up of a plurality of grounded collecting electrodes and a high voltage discharge electrode in spaced relationship to each other and which are suspended from a supporting structure in a precipitator shell.
A uni-directional high potential field is set up between the collecting and discharge electrodes and at a critical voltage a corona discharge takes place resulting in an ion discharge. The bulk of the foreign particles in the gas stream passing between the electrodes become negatively charged as a result of the ion discharge and, consequently, are attracted to the grounded collecting electrodes and accumulate thereon, although a few of the particles may be attracted to the discharge electrodes.
Rappers or vibrators, such as described and illustrated in Pennington U.S. Pat. No. 3,030,753, are attached to the collecting and discharge electrode support structure to remove the particles collected thereon by producing vibrations of the electrodes and causing the accumulated particles to jar or vibrate loose and fall downwardly of their own weight into suitable collecting means well known in the art.
The collecting electrodes are usually constructed of flat metal plates suitably connected together, whereas the discharge electrodes have taken the form of elongated wires, ribbons or rods connected to the support structure in any one of several ways, such as bolting, welding, or clamping the electrode to the supporting structure.
It is well known, however, that the discharge electrodes are more sensitive to rapping or vibrating than the collecting electrodes and therefore have required the most attention as to the method of suspension because of fatigue and subsequent mechanical failure. It is also well known that rapping of the discharge electrodes imparts a relatively large deflection to the electrodes, resulting in severe localized stresses occurring at the upper and lower points of suspension of the electrodes. It is at these points that breakage and failure of the electrodes have for the most part been concentrated. Conventional connecting or suspensory means generally have made little or no provision to reduce or obviate these highly stressed conditions. Consequently, when a discharge electrode fails, it is often necessary to interrupt the operation of the precipitator to repair or replace the broken electrode, otherwise, a hazardous and undesirable arc-over is likely to occur between the broken electrode and the grounded collecting electrode. Such interruptions are not only costly, but in addition, repairing or replacing the broken electrode is usually difficult.
Present methods of connecting the discharge electrodes to the support structure or weight means create difficulties of their own, particularly difficulty in replacing broken electrode wires. Replacing bolted connections is time-consuming and often proves destructive to the support structure or weight means when attempts are made to remove or dislodge rusted bolts. Additionally, it is very time-consuming and expensive to replace electrode wires that are attached to the support structure and weights by bolt means or similar means.
In order to overcome these problems, an electrode wire discharge assembly was developed in which the electrode wires has its opposite ends terminating axially within two identical shrouds, each of the shrouds is shaped as an elongated rod terminating in a combined frusto-cone and enlarged button head. In assembly, one of the frusto-conical ends of the shroud seats on a keyhole slot located in a support frame while the other frusto-conical end of the shroud seats on the edges of a transverse slot located in a cylindrical weight adapted to receive the shroud. While such a wire electrode offers advantages over the prior art wire electrodes, they can only be used in precipitators in which the support system and weights are designed to cooperate with the frusto-conical shaped shrouded electrodes. Accordingly, it is the object of this invention to provide an adapter so that such improved wire electrodes and their ease of changing can be used with existing precipitators.